[unreadable] Individuals with Down syndrome (DS) have mild to moderate mental retardation, short stature and associated overweight. Weight loss interventions for children and adolescents with DS have not been studied sufficiently. With typical children, interventions in which parents are taught to use behavior modification to improve dietary and activity habits have been effective. Research is needed to investigate behavioral weight reduction with a new population, adolescents with DS. This study will compare the effectiveness of: 1) a Parent Supported Weight Reduction intervention (PSWR) that combines behavior modification and nutrition/activity education (NAE), with 2) NAE alone and 3) a Wait List (WL) control group. The primary Specific Aim is to determine whether adolescents with DS in the PSWR condition lose more weight and body fat than participants in NAE alone or WL. Two secondary Specific Aims are to determine whether adolescents in PSWR are more successful than those in NAE alone in: 1) meeting the prescribed number of servings in specified food groups, and 2) increasing physical activity. Seventy-two (72) adolescents with DS between 13-18 who are overweight (body mass index > 95th percentile for age and gender), and their parents, will be randomly assigned to one of three groups: PSWR, NAE-alone or WL. PSWR and NAE-alone groups will receive a 6-month intervention, meeting weekly for 10 wks (90 min sessions), then bi-weekly and monthly. NAE components in both groups will be conducted by a nutrition educator, supervised by a nutritionist/registered dietician and a physical therapist, both with expertise in DS (co-investigators). Behavioral components of PSWR will be conducted by a behavioral psychologist with expertise in DS (the PI). Following the 6-month intervention, participants in PSWR and NAE-alone will be followed over a 6-month maintenance phase. We will measure and compare changes in body fat (BIA), BMI-z score, number of servings in specified food groups, and activity (accelerometer) at pre-intervention, 10 wks, 6 mos (post intervention) and 12 mos (maintenance). Participants in WL will not receive a concurrent intervention, but will participate in BIA and BMI-z measurement at the same intervals. WL participants will be offered the most effective intervention (PSWR or NAE) in Year 2. Our long-term goals with this project are to: 1) learn more about health promotion in families of children with DS and other developmental disabilities, and 2) develop an R01 application to investigate processes associated with long-term behavior change and health, especially adolescent-managed intervention [unreadable] [unreadable] [unreadable]